Physics Unit6: Work and Energy - 题库网 (tiku.one)

1#

What is the correct unit of work expressed in SI un(3t53v u3dj m0dt/8nu -lkct p(crr jcits?

A. $kg m/s^2$

B. $kg m^{2}/s$

C. $kg m^{2}/s^2$

D. $kg^2 m/s^2$

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2#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Can work be done on a system if there is no mxm)dk7ebu i j9d.2om(otion?

A. Yes, if an outside force is provided.

B. Yes, since motion is only relative.

C. No, since a system which is not moving has no energy.

D. No, because of the way work is defined.

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3#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you push twice as hard against a stationary brick wall, the am (vqh ph.01henount of work youeqvh.n (0p 1hh do

A. doubles.

B. is cut in half.

C. remains constant but non-zero.

D. remains constant at zero.

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4#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 50-N object was lifted 2.0 m vertically and is b9 a+qq,wtw2 h9twb1cbeing held there. How much work is being done in holding the boxbwt1c,+wha 99 qwbqt2 in this position?

A. more than 100 J

B. 100 J

C. less than 100 J, but more than 0 J

D. 0 J

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5#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If you walk 5.0 m horizontally forward at a constu+ uy3)qu+ ase t4,rs 52xume.( mbgzmant velocity carrying a 10-N object, the amount of workresz+gq4),(2 mmubt3u5. x ymaue+s u you do is

A. more than 50 J.

B. equal to 50 J.

C. less than 50 J, but more than 0 J.

D. zero.

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6#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A container of water is lifted vertically 3.0 m then returned to its orij5, ltsa;j 5l:.8jtq oq:lh) jwib0fzginal position. bq5. tsj;8:5 izl,0j jflhqj a:)otwl If the total weight is 30 N, how much work was done?

A. $45 \; J$

B. $90 \; J$

C. $180 \; J$

D. No work was done.

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7#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Does the centripetal force actin xtoyt07tt54 sg on an object do work on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

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8#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You throw a ball straight up. Compare the sign of the work done by gravit irk(2dm:ex:d y whilei( ekm: dd:x2r the ball goes up with the sign of the work done by gravity while it goes down.

A. Work is + on the way up and + on the way down.

B. Work is + on the way up and - on the way down.

C. Work is - on the way up and + on the way down.

D. Work is - on the way up and - on the way down.

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9#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The area under the curve, on a Force versus position (F vs. x) graph, repri3mvkkvj t*5d/ ord2u5dis81esentsvum*d123jki5 k diordsv/85t

A. work.

B. kinetic energy.

C. power.

D. potential energy.

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10#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

On a plot of Force versus position (F vs. x),w47c0iu5ts fsq f;a: m what represents the work done by the force Fc iw4fum;t0a5q:f 7ss ?

A. the slope of the curve

B. the length of the curve

C. the area under the curve

D. the product of the maximum force times the maximum x

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11#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; mv^2$ is

A. the kinetic energy of the object.

B. the potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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12#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is positive, then the object's kinetic en4xy5 au wc838e( 1xg ukty6nbpergy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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13#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on tl,o(v -8 8vg2 4xhlo,sk js )qsy:/axjn6wpx an object is negative, then the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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14#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If the net work done on an object is zero, g0x ;g-d6hqtb1cotb q 8: yk:ethen the object's kinetic energy

A. decreases.

B. remains the same.

C. increases.

D. is zero.

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15#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A truck weighs twice as much as a car, and is movikgt0,epg/si ; ng at twice the speed of the car. Which statement is true about the tru g/epksi,0t;gck's kinetic energy compared to that of the car?

A. All that can be said is that the truck has more kinetic energy.

B. The truck has twice the kinetic energy of the car.

C. The truck has 4 times the kinetic energy of the car.

D. The truck has 8 times the kinetic energy of the car.

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16#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Car J moves twice as fast as car K, and car J has hal(9;aans vjk.a,- v ebdf the mass of car K. The kinetic energy of (kned; sa,a 9jvvb-.acar J, compared to car K is

A. the same.

B. 2 to 1.

C. 4 to 1.

D. 1 to 2.

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17#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object hits a wall and bounces back with half of its original spee83d f,:jy/ymmnqq 0hzd. What is the ratio of the final kinetic energy to the initial kinetic energyf /d,0y qh3j8zqyn: mm?

A. \frac{1}{2} \;

B. 1/4

C. 2

D. 4

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18#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A brick is moving at a speed of 3 m/s and a pebble is moving a 6et+ z*fbt)rle:g8y og,* pe86ujnks t a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratp* 8ke+6 et*ug)sb: gtnz,j8lyr oe6fio of the brick's mass to the rock's mass?

A. 25 to 9

B. 5 to 3

C. 12.5 to 4.5

D. 3 to 5

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19#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.0-kg mass is moving with lsscs59s(z1tkem9 d1speed 2.0 m/s. A 1.0-kg mass is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travcs1tm(z 5sd 1 9kle9ssels the greater distance before stopping?

A. the 4.0-kg mass

B. the 1.0-kg mass

C. Both travel the same distance.

D. cannot be determined from the information given

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20#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You slam on the brakes of your car in a panic, and skid a.v yhyb4psi35)tr a /c certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded, undp/a). t4b cyyvh 53srier the same conditions?

A. It would have skidded 4 times farther.

B. It would have skidded twice as far.

C. It would have skidded 1.4 times farther.

D. It is impossible to tell from the information given.

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21#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A planet of constant mass orbits the Sun in an elliptical orbit. Neglecting anyeq /k b2oem(c. eo.m-ofyo+ ,f friction effects, what happens to the planet.-( ,mcqobeo/e2ef fmy+oo .k's kinetic energy?

A. It remains constant.

B. It increases continually.

C. It decreases continually.

D. It increases when the planet approaches the Sun, and decreases when it moves farther away.

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22#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the work-energy pri5hgol 1n)uz1q nciple.

该题自我估分: (必填) (满分:1.0分)

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23#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity mgy is

A. the kinetic energy of the object.

B. the gravitational potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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24#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity $\frac{1}{2} \; kx^2$ is

A. the kinetic energy of the object.

B. the elastic potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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25#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Is it possible for a system to thw3.b f62r78hy ugvtxtgp3so*h9i 8have negative potential energy?

A. Yes, as long as the total energy is positive.

B. Yes, since the choice of the zero of potential energy is arbitrary.

C. No, because the kinetic energy of a system must equal its potential energy.

D. No, because this would have no physical meaning.

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26#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is released from rest a height h above thhldn 3t i. 3d- vx/0 sq1rkr-+kfiv+tpe ground. A second object with four times the mass of the first if released from the same height. The xlrvd- ti k 1pn-df3vi3t +s.+0hq/krpotential energy of the second object compared to the first is

A. one-fourth as much.

B. one-half as much.

C. twice as much.

D. four times as much.

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27#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 0.200-kg mass attached to the end of a spring causes it to -1urv 1clo/y6y *cc)(hjf fjg stretch 5.0 cm. If another 0.200-kg mass yf*j gvc6j1r1/chf( )ou-cl yis added to the spring, the potential energy of the spring will be

A. the same.

B. twice as much.

C. 3 times as much.

D. 4 times as much.

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28#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The total mechanical energko 1 qcmtkbiidn 6*,2vh-x7a 8jw(-vry of a system

A. is equally divided between kinetic energy and potential energy.

B. is either all kinetic energy or all potential energy, at any one instant.

C. can never be negative.

D. is constant, only if conservative forces act.

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29#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An acorn falls from a tree. Compare its kineti(1l8 ng s(b1licr-u4 nxslw4 uc energy K, to its potential energy U.ux1-1n(4lwcg8lsri 4n(lsb u

A. K increases and U decreases.

B. K decreases and U decreases.

C. K increases and U increases.

D. K decreases and U increases.

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30#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Describe the energy of a car driving uy.i5 kul ef h ;-ku1j*c1fg.lnp a hill.

A. entirely kinetic

B. entirely potential

C. both kinetic and potential

D. gravitational

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31#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A lightweight object ant 9dm.jkwb gu+nk)u*; qc.+r+wvr 2wvd a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill. Which rises to a *r )uqwvc tr db g+;k.vmj2w+u w9n+.kgreater height?

A. The heavy object, because it has greater kinetic energy.

B. The lightweight object, because it weighs less.

C. They both slide to the same height.

D. cannot be determined from the information given

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32#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Consider two masses eh s+th nl3*z8$m_{1}$ and $m_{2}$ at the top of two frictionless inclined planes. Both masses start from rest at the same height. However, the plane on which $m_{1}$ sits is at an angle of $30^{\circ}$ with the horizontal, while the plane on which $m_{2}$ sits is at $60^{\circ}$. If the masses are released, which is going faster at the bottom of its plane?

A. $m_{1}$

B. $m_{2}$

C. They both are going the same speed.

D. cannot be determined without knowing the masses

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33#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the principle of conservation of mechanical energy s5+ixjedh/. an8jc; kfor conservative forces;ke+8h/.d acjx 5ij ns.

该题自我估分: (必填) (满分:1.0分)

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34#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball falls from the top o0kp/yr;ld j4xf a building, through the air (air friction is present), to the ground below. How does the kinetic energy (K) just before striking the ground compy r /jkp;d40xlare to the potential energy (U) at the top of the building?

A. K is equal to U.

B. K is greater than U.

C. K is less than U.

D. It is impossible to tell.

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35#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and gains 30 J of kinetic energy. Do not ignore air otw z(lw/-tx*jg -2uvresistance. How much gr*l-wzw-/guxt j v2(toavitational potential energy did the ball lose?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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36#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A ball drops some distance and loses 30 J of gravitationali m5 xa5soq*75vv s-lt potential energy. Do not ignore air resista7* 5q55xvovsaltsim- nce. How much kinetic energy did the ball gain?

A. more than 30 J

B. exactly 30 J

C. less than 30 J

D. cannot be determined from the information given

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37#

问答题 ( 1.0 分) 切至整卷模式搜藏此题

State the law of conservation of energy.q w8k,slpbe5iaj0209yv6l rc

该题自我估分: (必填) (满分:1.0分)

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38#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The quantity Fd/t is fd2x-cx7sq;.b *ursd

A. the kinetic energy of the object.

B. the potential energy of the object.

C. the work done on the object by the force.

D. the power supplied to the object by the force.

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39#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What is the correct unit of power expressed in d *r 11.jwkfrzSI units?

A. $kg m/s^2$

B. $kg m^{2}/s^2$

C. $kg m^{2}/s^3$

D. $kg^2 m/s^2$

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40#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Of the following, which is not a unit ei y10(fpo q9.4lsjqiof power?

A. watt/second

B. newton-meter/second

C. joule/second

D. watt

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41#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Compared to yesterday, you did 3 times the w qva ys 4df lookzn*2pki.q 5 c8f1ippo4-))3tork in one-third the time. To do so, your power output must have 8 p23 psk1dlon kfo)o). 5iq*-fztv4acipy 4qbeen

A. the same as yesterday's power output.

B. one-third of yesterday's power output.

C. 3 times yesterday's power output.

D. 9 times yesterday's power output.

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42#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

To accelerate your car at a wnj djblwve( z2m 8wv h2j8 dbgw;9,10constant acceleration, the car's engine must

A. maintain a constant power output.

B. develop ever-decreasing power.

C. develop ever-increasing power.

D. maintain a constant turning speed.

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43#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object is lifted vertically 2.0 m and held there. If thip y7vu)je3 k3e object weighs 90 N, 73j3 yviep)ukhow much work was done in lifting it?

A. $360 \; J$

B. $180 \; J$

C. $90 \; J$

D. $0 \; J$

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44#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

You lift a 10-N physics boo tkv eaa+bk:s*/f2n s7k up in the air a distance of 1.0 m, at a constant velocity of 0.50 m/s. What is the work vfe 72t/+a*nas kb:sk done by the weight of the book?

A. +10 J

B. -10 J

C. +5.0 J

D. -5.0 J

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45#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a dis-scabn3x m, 6z/ a-qezbqx.;wvsv; m *tance of 5 ,-wn;xb;* szaxq 3za6.qv embm/cs-v0.0 m. What is the work done by the 5500 N force?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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46#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for a dis63vhviyrd p/ nsr b:r6dvo+4b) ms k3,tancerr6:rd )ks4 ,nhp doym i 3bb6vsvv/+3 of 50.0 m. What is the work done by the weight of the elevator?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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47#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 500-kg elevator is pulled upward with a constant force of 5500 N for ejv +2sl2k51xosfrpy(;/ - an ,woploa distance of 50.0 m. What e,;12px l os5v wklfsjr+n o(o2 -ap/yis the net work done on the elevator?

A. $2.75 \times 10^{5} \; J$

B. $-2.45 \times 10^{5} \; J$

C. $3.00 \times 10^{4} \; J$

D. $-5.20 \times 10^{5} \; J$

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48#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30-N box is pulled 6.0 7hb*:ne)ld k jhukn 4b(kg6i4 m up along a $37^{\circ}$ inclined plane. What is the work done by the weight (gravitational force) of the box?

A. $-11 \; J$

B. $-1.1 \times 10^{2} \; J$

C. $-1.4 \times 10^{2} \; J$

D. $-1.8 \times 10^{2} \; J$

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49#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 4.00-kg box of fruit slides 8.0 m down a ramp, incldg 4)l4f amn1qined at $30^{\circ}$ from the horizontal. If the box slides at a constant velocity of 5.00 m/s, what is the work done by the weight of the box?

A. $157 \; J$

B. $-157 \; J + 78.4 \; J$

C. $78.4 \; J$

D. $-78.4 \; J$

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50#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Matthew pulls his little sister Sarah in a sled on 8pmib(g)6pb ran icy surface (assume no friction), with a force of 60.0 N at (p8 b) rbgimp6an angle of $37^{\circ}$ upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

A. $185 \; J$

B. $433 \; J$

C. $575 \; J$

D. $720 \; J$

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51#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Fig.l6vdx-tg2mc8g:eph : 6-1 shows the force versus the object's position. Find the l::d-2v6hmtg8xpge c work done when the object moves from 0 to 2.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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52#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of the force. The graph in Figo/om b 1uxlt0s wp4/j). 6-1 shows the force versus the object's position. Find the work done when the object wlst)bm x1u0/o 4 op/jmoves from 2.0 to 4.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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53#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the dired(okd r ,*ok qy19if/zction of the force. The graph in Fig. 6-1 shows1oy(rfk* qk/od z, d9i the force versus the object's position. Find the work done when the object moves from 4.0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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54#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force moves an object in the direction of tbf 2jyilv j.8gce0 1-nhe force. The graph in Fig. 6-1 shows the force versus the object's position..g- 0 2njl1ceyfib8v j Find the work done when the object moves from 0 to 6.0 m.

本题所包含的其它图片:

A. $20 \; J$

B. $40 \; J$

C. $60 \; J$

D. $80 \; J$

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55#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is appli*u5ke vr ,h.mxed to move a 55-kg cart (initially at rest) across a 10 m level surface. Wh*rhkmu xv5, .eat is the final kinetic energy of the cart?

A. $1.0 \times 10^{3} \; J$

B. $2.0 \times 10^{3} \; J$

C. $2.7 \times 10^{3} \; J$

D. $4.0 \times 10^{3} \; J$

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56#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A horizontal force of 200 N is applied to v0se(d.sc e:tan:k8 d8m-, as8d gjbnmove a 55-kg cart (initially at rest) acrjg0ke8 da8sbs-tcn(.:,e8ddv: na s moss a 10 m level surface. What is the final speed of the cart?

A. 73 m/s

B. 36 m/s

C. 8.5 m/s

D. 6.0 m/s

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57#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass is moving with a speed of 5.0 m/s. How much workp joqo3:es2e9to)(ww is required to stop the mwq3w2o:sj9 t)oe(eop ass?

A. $50 \; J$

B. $75 \; J$

C. $100 \; J$

D. $125 \; J$

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58#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

If it takes 50 m to stop a car initialr 96l1a+xyobqj j/ pbsa 3kg5,ly moving at 25 m/s, what distance is required to stop a car moving at 50 m/s under the same condition?y/5,1rb 3l6xo aak j+bjqgs9 p

A. $50 \; m$

B. $100 \; m$

C. $200 \; m$

D. $400 \; m$

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59#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring-driven dart gun propels af*s 9l lgl ;;qxnwi:;z 10-g dart. It is cocked by exerting a force of 20 N over a distance of 5.0 cm. With;;g llzw;*x f9qs:nl i what speed will the dart leave the gun, assuming the spring has negligible mass?

A. 10 m/s

B. 14 m/s

C. 17 m/s

D. 20 m/s

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60#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 100-N force has a horizontal component of 80 N and a vertical component o+a * tao(*rpcwf 60 N. The force is applieap **(wac t+ord to a box which rests on a level frictionless floor. The cart starts from rest, and moves 2.0 m horizontally along the floor. What is the cart's final kinetic energy?

A. $200 \; J$

B. $160 \; J$

C. $120 \; J$

D. zero

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61#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An arrow of mass 20 g is shot horizontal 42imne g4gia4c-f2hp, jhp+jly into a bale of hay, striking the hay with a velocity of 60 m/s. It penetrates a depth of 20 cm before stopping. What is the av4p4 a ifg4 hn,p2g-hc+ejj2 mierage stopping force acting on the arrow?

A. $45 \; N$

B. $90 \; N$

C. $180 \; N$

D. $360 \; N$

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62#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 15.0-kg object is moved from a height of 7.00 m ab t4x r.deetbi g8:ne235t d(uuove a floor to a height of 13.0 m above the floor. What is the change in8u. eb5:ue(2ttxnr4 gi3dt de gravitational potential energy?

A. zero

B. 1030 J

C. 1176 J

D. 1910 J

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63#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 400-N box is pushed up an inclined plaf) n /2cgloi*fne. The plane is 4.0 m long and rises 2.0 m. If the plane is frictionlesso/l)* inffgc2, how much work was done by the push?

A. $1600 \; J$

B. $800 \; J$

C. $400 \; J$

D. $100 \; J$

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64#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-kg mass, hung onto a spring, causes the spring to stretch 2.0 cm. Wtp v xq*,ub1- at5qi)omt4( iuhat is the *q vtq4, mix-ta )b1uot5u(pispring constant?

A. $4.9 \times 10^{3} \; N/m$

B. $5.0 \times 10^{3} \; N/m$

C. 20 N/m

D. 2.0 N/m

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65#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring is characterized by a spring constant of 60 N/m.w 9 y3*uw3xhqi How much potential energy does it store, whenu y*3qxwiw9 h3 stretched by 1.0 cm?

A. $3.0 \times 10^{-3} \; J$

B. $0.30 \; J$

C. $60 \; J$

D. $600 \; J$

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66#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

Calculate the work required to compress an initially uncompres85;x -p kkrevwsed spring with a spring constant of 25 N/m byv- xer5kp8w;k 10 cm.

A. $0.10 \; J$

B. $0.13 \; J$

C. $0.17 \; J$

D. $0.25 \; J$

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67#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

What work is required to stretch a spring of spring constant 40 N /cwdmvlx0 hfm/u-5qn8j 5 0qg/m from x = 0.20 m to 0.25 m? (Assume thqfcj05gmw 0vh/l 5n /u8mqx-de unstretched position is at x = 0.)

A. $0.45 \; J$

B. $0.80 \; J$

C. $1.3 \; J$

D. $0.050 \; J$

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68#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A spring with a spring constant of 15 N7evdyk )wqjr8 2qmoi :f*e9q+/m is initially compressed by 3.0 cm. How much wej k7 *+d: f8rmqovyq)2 ieq9work is required to compress the spring an additional 4.0 cm?

A. $0.0068 \; J$

B. $0.012 \; J$

C. $0.024 \; J$

D. $0.030 \; J$

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69#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from re*ddqiod2: ;u yst from the top of a 50-m high slope. What is the speed of the slier on reaching the bo:;idy2q*udo dttom of the slope? (Neglect friction.)

A. 22 m/s

B. 31 m/s

C. 9.8 m/s

D. 41 m/s

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70#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A skier, of mass 40 kg, pushes off the top 7z 7qq)e 7kan kg07imyof a hill with an initial speed of 4.0 m/s. Neglecting friction, how fast will she be moving after d)iy zgkk70n7eqqa 77mropping 10 m in elevation?

A. 7.3 m/s

B. 15 m/s

C. 49 m/s

D. 196 m/s

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71#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An object slides down a frictionless inuvohqi4d: 3pe:,: fipclined plane. At the bottom, it has a speed of 9.80 m/s. What is t:hdpeu:p q:, fovi43 ihe vertical height of the plane?

A. $19.6 \; m$

B. $9.80 \; m$

C. $4.90 \; m$

D. $2.45 \; m$

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72#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1.0-kg ball falls to the floor. When it is 0.70 m abo 4o3rj9w9sg azt lm 1cozj;0*mve the floor, its potential energy exactly equals its kinetic energy. How fast is it movic9go4m *a13 srz9jj0low;tmz ng?

A. 3.7 m/s

B. 6.9 m/s

C. 14 m/s

D. 45 m/s

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73#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A toy rocket, weighing 10 N, blasts a lk.ja,(/:fslzrq /,ui3e1ubn3lx ostraight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical eneruasl3ek,xfn.qrbi //,o3a: ll (1juzgy is 140 J. To what vertical height does it rise?

A. $1.0 \; m$

B. $10 \; m$

C. $14 \; m$

D. $24 \; m$

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74#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A projectile of mass m leaves the groun)ijgf;j- m ky)r n/,asd with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, d jk-f)ga ;srimj, )yn/id it rise?

A. $\frac{220}{mg} \; m$

B. $\frac{120}{mg} \; m$

C. $\frac{100}{mg} \; m$

D. Impossible to determine without knowing the angle of launch

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75#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts from rest at as q.:0+pc6kftmwx7b a point 45 m above the bottom of a dip (See Fig. 6-2). Neglect frictionwqc0bk m7a p x6:.tf+s, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 17 m/s

C. 24 m/s

D. 30 m/s

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76#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts with a speed of 5.0 m/s at a point 45 m abo(-f 5o(g9 r1 :sczfcd;tavwzn ve the bottom of a dip (See Fig. 6-2). Neglect friction, what will be the spen:tzaffd9 ; zr (o5cgcvs(-w1ed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?

本题所包含的其它图片:

A. 12 m/s

B. 14 m/s

C. 16 m/s

D. 18 m/s

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77#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A roller coaster starts at a point 30 m above the bottom of a dip with w pvh(2m w:d yf95gg0ia speed of 25 m/s (See Fig. 6-2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bgv(iyfw 02gw h:9 md5pottom of the dip?

本题所包含的其它图片:

A. 14 m/s

B. 16 m/s

C. 18 m/s

D. 20 m/s

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78#

( 1.0 分) 切至整卷模式搜藏此题

What is the minimum speed of the5lys;zk o hu5 a74/gms ball at the bottom of its swing (point

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79#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A:2.2 m/s

A. 3.1 m/s

B. 4.4 m/s

C. 4.9 m/s

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80#

( 1.0 分) 切至整卷模式搜藏此题

难度:2

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81#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A pendulum of length 50 c/q qztn xrw qbyuh-38m(8+0r ;l )kttam is pulled 30 cm away from the vertical axis and released from rest. What will be its speed at the zr-0x tu +y w/ bkqat)trnq3hl(; 8qm8bottom of its swing?

A. 0.50 m/s

B. 0.79 m/s

C. 1.2 m/s

D. 1.4 m/s

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82#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car moving at 25 m/s hits an initially6h hxfb (k08ci kk0se/ uncompressed horizontal spring with spring constant of k86e h(f0hc sbkk/0xi$2.0 \times 10^6 \; N/m$. What is the maximum compression of the spring? (Neglect the mass of the spring.)

A. $0.17 \; m$

B. $0.34 \; m$

C. $0.51 \; m$

D. $0.68 \; m$

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83#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A driver, traveling at 22 m/s, slowkw5d jwry poucq fx-:yk, - u352(nno2s down her 2000 kg car to stop for a red light. What work is done by tonx d(-wn3ykf-,2jw yr uu52:poq5 ckhe friction force against the wheels?

A. $-2.2 \times 10^{4} \; J$

B. $-4.4 \times 10^{4} \; J$

C. $-4.84 \times 10^{5} \; J$

D. $-9.68 \times 10^{5} \; J$

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84#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

The kinetic friction force between a 60.0-kg object and a horizontal surfa:m,o*(t 2viz dllnh:bce is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before comingz,*nl ivo(b:dl:tm h 2 to a stop?

A. $15.0 \; m$

B. $30.0 \; m$

C. $375 \; m$

D. $750 \; m$

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85#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 12-kg object is moving on a rough, level surface. It has 24 J ofa7l 91bfkz ) hr)iyr/k kinetic energy. The friction force on it is a constant 0.50 N. z9 rkf1/)lkry)ib ah7 How far will it slide?

A. $2.0 \; m$

B. $12 \; m$

C. $24 \; m$

D. $48 \; m$

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86#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A force of 10 N is applied horizontal0 tnhdc/qn7k +ly to a 2.0-kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 10 m, what is the chndkctn /0+ q7hange in its kinetic energy?

A. $20 \; J$

B. $39 \; J$

C. $46 \; J$

D. $61 \; J$

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87#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 60-kg skier starts from rest from the - su/gdacbt7 xvr;*c4top of a 50-m high slope. If the work done by fa*xbdus v/tgr; -cc74riction is $-6.0 \times 10^{3} \; J$, what is the speed of the skier on reaching the bottom of the slope?

A. 17 m/s

B. 24 m/s

C. 34 m/s

D. 31 m/s

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88#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

An 800-N box is pushed up an inclined he5jzb k,dy xg4-i*wh92qo9fplane. The plane is 4.0 m long and rises 2.hj h9iw oy25f4,ek-b*9xgdqz 0 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the box?

A. $0 \; N$

B. non-zero, but less than 400 N

C. $400 \; N$

D. greater than 400 N

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89#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 2.0-kg mass is released from rest at the top of sny7 +vms*f(oa plane inclined at 20e above horizontal. The+7(nvss*my fo coefficient of kinetic friction between the mass and the plane is 0.20. What will be the speed of the mass after sliding 4.0 m along the plane?

A. 2.2 m/s

B. 3.0 m/s

C. 3.5 m/s

D. 5.2 m/s

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90#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 30.0-N stone is dropped from a height of 10.0 m, and. dmtkly7 i5l aj8+jp6 strikes the ground with a vj+l.m 6pkdy8at7ij l5elocity of 7.00 m/s. What average force of air friction acts on it as it falls?

A. $22.5 \; N$

B. $75.0 \; N$

C. $225 \; N$

D. $293 \; N$

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91#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

At what rate is a 60.0-kg boy using energy when he runs up a flight of s0 ufoww(njeva:3k9b. i15e zt tairs 109z wtw :f3kea 5jn(0buve1i.o .0-m high, in
8.00 s?

A. $75.0 \; W$

B. $735 \; W$

C. $4.80 \; kW$

D. $48 \; W$

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92#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 10-N force is needed to move an object with a constant velobdsc- c -l,xs.city of 5.0 m/s. What power must be delivec db-cx,-sls. red to the object by the force?

A. $0.50 \; W$

B. $1.0 \; W$

C. $50 \; W$

D. $100 \; W$

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93#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

How many joules of energy are used bs dbwdh5*/k pbx8ta/6/ z8daoy a 1.0 hp motor that runs for 1.0 hr? (1 hp = 746 W)/5 x8 zaadthp /d/b6k8o wd*bs

A. $3.6 \times 10^{3} \; J$

B. $2.7 \times 10^{6} \; J$

C. $4.5 \times 10^{4} \; J$

D. $4.8 \; J$

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94#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A cyclist does work at the rate of 500 W whiletli t7- nxt w cvsld0(oj2+xtz0)-u5i riding. How much force does her foot push withji-tzc(dui )st tx+v7xtlno0- 2 w50l when she is traveling at 8.0 m/s?

A. $31 \; N$

B. $63 \; N$

C. $80 \; N$

D. $4000 \; N$

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95#

单选题 ( 1.0 分) 切至整卷模式搜藏此题

A 1500-kg car accelerates fcgbky qk ic-*j f8u19n5 p*c.irom 0 to 25 m/s in 7.0 s. What is the average power y*p9nb8 c5fug.k jciicq1* k- delivered by the engine? (1 hp = 746 W)

A. $60 \; hp$

B. $70 \; hp$

C. $80 \; hp$

D. $90 \; hp$

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